Latest revision as of 14:38, 30 November 2021

Abstract

Bed joint reinforced repointing is a strengthening method often used in the Netherlands to counteract settlement damage. This strengthening technique consists of cutting a slot in the mortar joint and installing twisted steel bars embedded in a high-strength repair mortar. Due to the increase in seismic activities, triggered by gas extraction in the region of Groningen (northern part of the Netherlands), it is of interest to investigate whether this strengthening technique is efficient against seismic load. In order to characterize the performance of the bed joint reinforced repointing using twisted steel bars, an experimental campaign was conducted at Delft University of Technology. A quasi-static cyclic in-plane test on a full-scale wall was performed; similar tests on unstrengthened specimens were available from a previous experimental campaign [1][2] and were used for comparison. Moreover, small scale pull-out tests were performed to study the interaction between the steel bars and the repair mortar. By comparing the response of unstrengthened and strengthened masonry specimens, it is observed that the use of bed joint reinforced repointing can provide an increase in terms of ductility and displacement capacity, but not in terms of force capacity. Regarding the serviceability limit state, a reduction in crack width and an increase of load at onset of cracking were observed. The preliminary information obtained for the presented case study provides the ground for futher research as well as benchmark for numerical modelling.

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References

[1]Korswagen, P., Longo, M. and Meulman, E. Damage sensitivity of Groningen masonry structures – experimental and computational studies. Delft University of Technology. Report no. C31B69WP0-12, version 1, 30 December 2017.

[2]Korswagen, P., Longo, M. and Meulman, E. Damage sensitivity of Groningen masonry structures – experimental and computational studies. Delft University of Technology. Report no. C31B69WP0-13, version 1, 21 December 2018.

[3]Valluzzi M.R., Binda L., Modena C. (2005). Mechanical behaviour of historic masonry structures strengthened by bed joints structural repointing. Construction and Building Materials, 19(2005), 63-73.

[4]NIKER (2010), New integrated knowledge based approaches to the protection of cultural heritage from earthquake-induced risk.

[5]Ismail N., Petersen R.B., Masia M.J., Ingham J. (2011). Diagonal shear behaviour of unreinforced masonry wallets strengthened using twisted steel bars. Construction and Building Materials, 25(2011), 4386-4393.

[6]Licciardello L., Esposito R. (2019). Experimental study on unreinforced masonry strengthened with bed joint reinforcement. Delft University of Technology. Report no. CM1B07-2, version 1, 28 November 2019.

[7]Kallioras S., Guerrini G., Tomassetti U., Marchesi B., Penna A., Graziotti F., Magenes G. (2017). Experimental seismic performance of a full-scale unreinforced clay-masonry building with flexible timber diaphragms. Engineering Structures, 161(2018), 231-249.

[8]EN 772-1 (2000). Methods of test for masonry units - Part 1: Determination of compressive strength. Nederlands Normalisatie-instituit (NEN).

[9]NEN 6790 (2005). Technical principles for building structures-TGB 1990- Masonry structures - Basic requirements and calculation methods. Nederlands Normalisatie-instituit (NEN).

[10]EN 1015-11 (1999). Method of test for mortar for masonry – Part 11: Determination of flexural strength of hardened mortar. European Committee for Standardisation (CEN).

[11]EN 1052-1 (1998). Method of test masonry – Part 1: Determination of compressive strength. Nederlands Normalisatie-institute (NEN).

[12]EN 1052-5 (2005). Method of test masonry – Part 5: Determination of bond strength by bond wrench method. Nederlands Normalisatie-institute (NEN).

[13]EN 1052-3 (2002). Method of test masonry – Part 3: Determination of initial shear strength. Nederlands Normalisatie-institute (NEN).

[14]EN 12190 (2018). Products and systems for the protection and repair of concrete structures – Test methods – Determination of compressive strength of repair mortar.

[15]Moreira S., Ramos L.F., Csikai B. (2014). Bond behaviour of twisted stainless steel bars in mortar joints. 9th International Masonry Conference Proceedings, Guimaraes, Portugal.

[16]EN 1766 (2015). Products and systems for the protection and repair of concrete structures -Test methods – Reference concrete for testing. Nederlands Normalisatie-institute (NEN).

[17]Skroumpelou G., Messali F., Esposito R., Rots J.G. (2018). Mechanical characterization of wall tie connection in cavity walls. Proceedings of 10th Australian Masonry Conference, 11-14 February, Sideny Australia.

[18]Mariani, V. Numerical prediction and sensitivity studies of the shaking table test on EUC-BUILD-2. Delft University of Technology, 17 November 2016

[19]Magenes, G., Morandi, P. and Penna, A. (2008). In-plane cyclic tests of calcium silicate masonry walls. Proceedings of 12th International Brick/Block Masonry Conference, 18-20 February, Sydney Australia.